1. Field of the Invention
The invention relates generally to autostereoscopic displays, and particularly to a convex lenticular lens based autostereoscopic display which is convertible to a full resolution two dimensional image display.
2. Discussion of Related Art
Autostereoscopic imaging, that is, the formation of at least one stereoscopic image pair which can be perceived as a single three dimensional image without the need for color filter, polarizing, or other types of special glasses, can be accomplished by suitably aligning a lens array with the pixel columns of a two dimensional, electronic display. This method of autostereoscopic imaging is described in U.S. Pat. Nos. 5,083,199 (Borner), and 4,959,671 (Bass et al.), for example; and in numerous foreign and domestic publications. It is also appreciated, however, that the resulting autostereoscopic images are limited, at best, to one half the resolution of the two dimensional image on the display screen. This is due to the effect of the lenticular lens which sends left perspective images to the viewer's left eye viewing zone in front of the display screen and right perspective images to the viewer's right eye viewing zone in front of the screen. In other words, all of the light emitted from the pixel columns of the 2D display is divided between at least two or more images (a half resolution left eye image and a half resolution right eye image).
A problem arises when the electronic display is used both for two dimensional imaging applications such as word processing and spreadsheets, as well as three dimensional imaging applications, as many computer system displays are capable of. The lenticular optics for autostereoscopic imaging typically cut down on the screen resolution by at least a factor of one-half due to half of the display showing a left eye image and the other half of the display showing a right eye image. This has the effect of rendering the two dimensional images, such as text, difficult or impossible to interpret. Thus while the display system may well be capable of both two dimensional and three dimensional display modes, the hardware required for displaying autostereoscopic images typically results in either a dedicated two dimensional or three dimensional display system.
One solution to the problem is to provide a display with twice as many pixels in the horizontal direction, and to display 2D images using pairs of pixel columns. This solution, however, is expensive, and in some cases beyond current technology. It is also impractical for the ultimate system supplier who wishes to provide 3D capability to its systems because the display components are typically purchased as off the shelf displays which have standard resolution formats.
Furthermore, in autostereoscopic imaging systems such as those discussed above, the lenticular lens sheets used in combination with the electronic displays are typically permanently mounted to the display screen to maintain their necessary critical alignment with the pixel columns of the screen. For example, the pixels in common high resolution color LCDs and plasma displays of the type used in laptop and notebook computers are on the order of 0.1 mm. wide; and with an active display area of roughly 15 cm. by 20 cm., a misalignment of the lenticules by as little as 14 seconds of arc can cause noticeable degradation in 3D image viewability. Thus, it is impractical to simply remove and replace the lenticular lens from the display screen to switch between a two dimensional and an autostereoscopic viewing mode.
In appreciation of the forementioned problems, the inventor has recognized a need for the ability to convert a display system having the prerequisite imaging capability between a full resolution, two dimensional viewing mode and an autostereoscopic viewing mode in a convenient and cost effective manner.